The present disclosure relates to computer systems and to methods and apparatuses for frequency and voltage margining. Given the high speed of today's microprocessors and related circuitry, the signal edge rates and system bus speeds have increased to the point that oscilloscope measurements may not offer a true indicator of signal quality present at an integrated circuit die. Typically, to accurately measure signal quality, a silicon die has to be exposed and probed by an oscilloscope. While oscilloscopes have been used for many years to make these types of waveform measurements, the very high speed of today's circuitry makes an accurate measurement by most oscilloscopes a very difficult and error prone process.
A number of issues combine that may make accurate oscilloscope measurements difficult. One such factor is the capacitance loading of an oscilloscope probe that, by it's very nature, changes the input impedance seen by a signal. This increase in capacitance may in fact modify the observed signal to such a degree that it is unreliable and does not accurately reflect the actual signal during normal operation of a circuit. Additionally, an oscilloscope probe may introduce inductance effects which like capacitance effects modify the observed signal waveform such that what is observed also may not accurately reflect a waveform of a circuit in actual operation without being probed.
To address these issues and to accurately measure signal quality of a silicon die, the silicon die typically has to be exposed and probed by expensive high speed test equipment. This may be a very time consuming and destructive process and therefore is one to be avoided if practical.
One reason for doing system margining, such as frequency and voltage margining, is to monitor in the production process components and systems that may have deviated from their specifications, or may have performance trends that require investigation to understand. Identifying and capturing these systems may improve the customer's experience with the related products and may reduce the cost in dealing with problems before products that may be problematic are introduced into the field.
Such margining testing may in fact be the only practical solution to proactively address and resolve process drift issues to prevent product holds that could become a major revenue impact to a company. Therefore, the ability to perform real time system margining may become an important part of the design and production phase of products in the future. The present invention may address one or more of the above issues.